Now texture storage of images is defined by the alpha mode of the image. The
downside of this is that there can be artifacts near alpha edges where pixels
with zero alpha bleed in. It also adds more code complexity since image textures
are no longer all stored the same way.
This changes allows us to keep using sRGB texture formats, which have edge
darkening when stored with premultiplied alpha. Game engines seems to generally
do the same thing, and we want to be compatible with them.
This makes it easier to set up materials with emission and transparency.
Importers/exporters and add-ons are recommended to now use these rather than
creating separate transparent BSDF and emission nodes.
Cycles now uses the color space on the image datablock, and uses OpenColorIO
to convert to scene linear as needed. Byte images do not take extra memory,
they are compressed in scene linear + sRGB transfer function which in common
cases is a no-op.
Eevee and workbench were changed to work similar. Float images are stored as
scene linear. Byte images are compressed as scene linear + sRGB and stored in
a GL_SRGB8_ALPHA8 texture. From the GLSL shader side this means they are read
as scene linear, simplifying the code and taking advantage of hardware support.
Further, OpenGL image textures are now all stored with premultiplied alpha.
Eevee texture sampling looks a little different now because interpolation
happens premultiplied and in scene linear space.
Overlays and grease pencil work in sRGB space so those now have an extra
conversion to sRGB after reading from image textures. This is not particularly
elegant but as long as engines use different conventions, one or the other
needs to do conversion.
This change breaks compatibility for cases where multiple image texture nodes
were using the same image with different color space node settings. However it
gives more predictable behavior for baking and texture painting if save, load
and image editing operations have a single color space to handle.
Differential Revision: https://developer.blender.org/D4807
The wrong transformation was used. Add a new matrix specially for this case.
This also fix the Node texture coordinate that was suffering the same issue.
Thanks to Gabor Fekete for helping finding the issue.
Was caused by uninitialized variable. Also took the oportunity to use comp
swizzling instead of multiple assignment.
In this case, the generic vertex attribute is {0,0,0,1}. So we look for
this case.
This fixes black text objects with a normal map applied. Also this could
help porting sculpt mode drawing to Eevee without supporting normal
mapping.
Note that will just fix black meshes due to T61870 but objects will not
show their normal map. So it's not a fix for this issue.
This was due to environement not being rendered with alpha blending. So
color was still written and contributed to the final render color. Now
we multiply by background alpha so that it removes any background pixels
intensity.
For this reason this made the (incorrect) final premult unecessary.
Values outside the 0..1 range produce negative colors, so now clamp to that
range everywhere. Also fixes improper handling of hue > 2.0 in some places.
